I'd like to thank the patience of customers over this - as I said before, the main delay was the new fibre links between the London data centres we use, and we had planned to be at this stage late last year, before there were any capacity issues.
The good news is that the new switches are deployed (last Thursday). This took a bit longer than expected but was all done within the planned work window. Yesterday evening we were able to start using the new fibre links and relieve the congestion on our Talk Talk back-haul.
The next step is not quite what we originally expected. We were expecting to need more BT back-haul links, but the recent moves of many lines from BT to TT had meant we actually have enough capacity to both BT and TT for now.
Surprising the next bottleneck is the LNSs themselves. Only a few months ago we moved from 3 active LNSs to 4, and we have several more waiting to be plugged in. Sadly the original design linked the LNSs to BT back-haul, so we can't simply add more just yet - not without change.
The next step is therefore a change to the way we link to BT and TT back-haul, and that is planned for Sunday morning starting at 2am. This will mean that the number of BT links, and the number of TT links, and the number of LNSs will all become independent, and we can deploy new LNSs next week.
I hope that is one of the last major disruptive bits of work we have to do. Once we have that change, it will be possible to go back to our normal rolling over-night upgrades on LNSs when needed. It will also be possible to deploy new LNSs without major disruption.
After all of that we have to look carefully at our transit and peering - again, we have enough capacity for now, but it may need a bit of juggling to ensure no links are getting hot.
We can then take a bit of a step back and work out where we need more capacity next, and get it in place before needed.
The good news is that now the TT back-haul is not the issue, I am launching the Home::1 ADSL Terabyte service later today. Thank you for your patience.